This invention relates to methods of preparing dialkyl dicarbonates.
Dialkyl dicarbonates, also known as dialkyl pyrocarbonates, are useful as fermentation inhibitors in wines and fruit juices, as well as reagents in chemical syntheses. Several methods are known for preparing dialkyl dicarbonates, but these methods suffer from various disadvantages such as hazardous starting materials (such as phosgene), low yields, and cumbersome purification steps.
One interesting approach is that described in FR 1,483,460 (Shamshurin--Institut Khimii an Moldavskoissr, granted in 1967). The method of the French patent is to react an alkyl chloroformate with potassium or sodium carbonate in the presence of a tertiary amine as a catalyst. While this method is in many respects an improvement over the prior art which proceeded it, it nonetheless is less than an ideal solution. In particular, the purification step necessary to separate the dialkyl dicarbonate from the tertiary amine is rather cumbersome, and the overall process has a disappointingly low yield.
Accordingly, it would be desirable to have a process for preparing dialkyl dicarbonates, which process is safe and convenient to carry out and provides relatively high yields of desired product.